Dowel means for expansion joints



3 S heets-Sheet 2 w. F. scHuLZ Fiied Nov. 9, 1935 game rm ILHMH I IP HIDOWEL MEANS FOR EXPANSION JOINTS April 4, 1939.

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April 4, 1939.

W. F. SCHULZ DOWEL MEANS FOR EXPANSION JOINTS Filed Nov. 9, 1955 3Sheets-Sheet 3 Juan/Who'l Patented Apr. 4, 1939 UNITED STATES DOWELMEANS FOR EXPANSION JOINTS Walter F. Schulz, Youngstown, Ohio, assignorto Truscon Steel Company, Youngstown, Ohio, in. corporation of MichiganApplication November 9, 1935, Serial No. 49,103

'5 Claims.

This invention relates to dowel means for expansion joints providedbetween the concrete or similar slabs of roadway, floors and the like,for permitting relative horizontal movement of the slabs in 'a directionparallel to the length of the dowels only while preventing the same fromheaving or lifting one with respect to the other, or shifting relativelyin any direction.

Many dowel structures heretofore employed are open to variousobjections, such for example as the cost of production; expense ofinstallation preparatory to pouring the slab; and, also tomalfunctioning in use due to improper design which causes lines ofcleavage or breakage in the slabs, thereby quickly defeating the veryobject and purpose of the device itself. In most cases, current practicerequires the relatively close spacing of dowel bars across the jointstructure which is costly from the standpoint of the number of devicesused, and, furthermore, various expedients must be utilized to supportthe dowels when the joint forming structure is first laid across thesub-grade of the prospective roadway. These supports for the dowels arefor the most part located substantially at the ends of the dowel bar orrod, considerably remote from the joint forming structure, and obviouslynot only constitute an added expense, but also do not support or engagethe dowel at the proper point, namely directly adjacent the jointforming structure itself. Therefore, when the slab is poured and thepaving material is tamped close to the joint structure and about thedowels there is no support for the dowels where the greatest stress isconcentrated. Consequently in use, due to heavy rolling loads, theconcrete surrounding the dowel bars or rods adjacent the opposite sidesof the joint structure'is subjected to great stress which results in therapid breaking down of the concrete and the forming of bell-mouthedcavities about the dowels, the base or largest diameter portions ofthese cavities opening into the joint space and said cavitiesprogressively decreasing in diameter to points eventually extendingthroughout the length of the end portions of the dowels embedded in eachadjacent slab. Obviously, when this condition occurs, undesirable linesof cleavage are not only set up in the then unsupported ends of theslabs, resulting in cracks, but, after this condition once starts, itbecomes rapidly aggravated to the point that the dowel bars becomedeformed or twisted so as to further increase the destructive action ofthe dowels on the concrete, thereby resulting in exceedingly rapiddeterioration of the pavement.

Accordingly, the present invention has generally in view, the provisionof novel dowel means which may be used in connection wth any type ofvertical joint forming structure either of metal or other material andconsisting of relatively few 5 integrated parts which may be assembledwith the joint either in situ at the joint location in the roadway, orwhich may be pre-assembled adjacent the road building site and simplyplaced in position by the mere act of disposing the as- 10 sembled jointand dowel means at the predetermined joint location. In that connection,the arrangement is such that the entire structure will stand erectwithout the necessity of supplemental anchors, pins or other supportsand pour- 1 ing the concrete may proceed in an expeditious manner. Whenthe concrete is poured, the entire structure is so embedded in thefinished pavement that all of the vertical stresses are absorbed at theproper point, namely immediately adjacent the joint structure, and, fromthence are adequately distributed so as to avoid the setting up ofcleavage lines and preventing disintegration of the concrete at thelocation of the dowel bars.

More specifically, the invention contemplates a dowel structureincluding a horizontally disposed dowel bar or rod which passes throughthemedial portion of the joint structure and'has rigidly affixed to oneportion thereof, novel combined supporting, anchoring and loaddistributing means, while the opposite portion of the bar is intended tobe slidably received in a comple-. mental or mating supporting,anchoring, and load distributing element, suitable means being providedfor preventing the plastic concrete form 35 filling or otherwiseinterfering with the space provided in said element for the movement ofthe dowel. This arrangement makes it possible to fit one section of theanchoring means against one side of the joint structure and thentelescopically to apply the other section of the anchoring means havinga guide to the end of the dowel bar projecting through the other side01' the joint structure, so that when both sections are completelyassembled with reference to the expansion joint, the entire joint 'anddowel structure is completely self-sustaining and ready for emplacementin the roadway.

Another object of the invention is to provide a dowel structureincluding anchoring means having portions fitting closely adjacent thesides of the joint structure while other portions thereof are preferablydisposed in a vertical plane and at an angle inclining away from theopposite faces of the joint structureto be embedded in the concreteabove and below the horizontal plane of the dowel bar. Thus, thecombined supports and anchors may become completely embedded in theconcrete in such a way as to adequately distribute the stress ofsuperimposed loads over a maximum area of the concrete in the adjacentend of each slab and provide increased bearing value at the point ofgreatest bearing load, namely, where the dowel bar emerges from oppositesides of the joint structure, thereby avoiding the concentration ofshearing stresses in the slabs in the immediate vicinity of the dowelpins, and placing all of the concrete throughout the depth of the slabends in compression instead of partly in compression and partly intension, that is in compression above and tension below the line of thedowel pins, as occurs with structures of the objectionable typeheretofore referred to.

Further objects of the invention are to provide a strong dowel structurewhich requires the use of the least number of units across the roadway;to provide a compact joint and dowel assembly which utilizes a dowel barof substantially square or rectangular cross-section to obtain greaterbonding area on one end of the dowel and a greater bearing area on theother; to provide dowel guiding means having maximum strength in thedirection of superimposed loads; to provide dowel anchor elements whichmay be formed in a simple and expeditious manufacturing operation andlikewise assembled with respect to the dowel bar and the dowel barguiding means in a rigid and stable manner by welding, thereby providinga structure which in its installed condition gives maximum strength andrigidity to the ends of the paving slabs under all conditions of use.

With the above and other objects in view, which will become more fullyapparent as the nature of the invention is better understood, the sameconsists in the novel features of construction, combination andarrangement of parts as will be hereinafter more fully described,illustrated in the accompanying drawings and defined in the appendedclaims.

In the drawings, wherein like characters of reference denotecorresponding parts in related views:

Figure 1 is a transverse section through a joint constructed inaccordance with one practical embodiment of the invention.

Figure 2 is an end view of the joint forming units.

Figure 3 is atop plan view of one of the joint forming units.

Figure 4 is a perspective view showing the interfitting elements formingthe tubular structure tr; slidably receive one end portion of the dowelp n.

Figures 5, 6 and 7 are views similar to Figures 1, 2 and 3,respectively, illustrating an altemative embodiment of the invention;and

. Figure 8 is a view partly in elevation and partly in sectionillustrating a slightly modified form of the tubular element formingpieces.

According to the several embodiments of the invention shown in thedrawings, the present novel dowel means is intended to cooperate withany selected type of joint forming structure designated generally as Adisposed between the ad- .jacent end portions of adjacent concrete orsimilar slabs Iii-i of the roadway.. The novel dowel means is designatedgenerally as B and includes the dowel pin or bar H used in connectionwith the combined supporting, anchoring and load or stress distributingelements C which have special features and characteristics to be laterreferred to more in detail.

As shown, the dowel pin or bar II is preferably made of rectangularcross-section thereby to provide a greater bondingsurface for the end ofthe dowel which is embedded in the slab than if a round section wereused, and to also provide a greater bearing area in theguide or framemember l2 which forms a part of a tubular housing in which the free orunbonded end of the dowel moves or slides under expansion andcontraction of the slabs l0-lll. The guide I2 is preferably of arelatively heavy gauge strip of metal of U- shaped formation,horizontally disposed, with the edges thereof disposed sidewise so thatthe flat sides are disposed above and below the top and bottom faces ofthe dowel bar, thereby affording greater strength to the housing. Tocomplete the housing a light strip of metal III, also of U-shapedformation, is placed within the guide i2 but, as will be apparent fromthe drawings, the same is set at an angle of 90 with respect to themember l2. That is to say, a tubular housing structure is provided toslidably accommodate one end portion of the dowel bar or pin byinterfitting the two U-shaped pieces of metal designated as l2 and i3,the piece I! including upper and lower leg portions and the piece l3fitting between the leg portions of the piece l2 and including oppositeside or leg portions closing the sides of the space between the legportions of the piece l2. Since the piece 13 carries little or no loadand its main function is simply to provide closures for the sides of thespace between the legs of the piece l2, it may be formed of relativelylight sheet metal. on the other hand, since the legs of the pieces I2transmit any loads to which the slabs and the dowel pins-are subjected,said piece I! may be formed from metal amply thick and strong to carrysuch loads.

Regardless of the specific form of the tubular elements or structuresembedded in one or the other of the slabs and each slidablyaccommodating one end of a related dowel pin, the means for distributingloads and stresses over large areas of the slabs in the vicinity of thedowel pins comprises for each dowel pin unit, a load or stressdistributing member l4 rigid with the tubular element or structure oftheunit and a similar load or stress distributing member I rigid withthat end portion of the dowel pin opposite the end portion thereof whichis slidably engaged in the tubular element or structure of the unit anda similar load or stress distributing member l5 rigid with that endportion of the dowel pin opposite the end portion thereof which isslidably engaged in the tubular element or structure.

The load or stress distributing members l4 and I5 preferably, but notnecessarily, an duplicates of each other, and also serve as combinedsupporting and anchoring means for the dowel bars. As illustrated, eachmember is formed from a single length of rod of preferably, but notnecessarily, round section and comprises a horizontally disposed bottomportion l6 and a pair of arms l1, l1 extending upwardly and inwardlyfrom the ends of said bottom portion, respectively. The arms extendupwardly and inwardly to points where the space between them isapproximately equal to the width or thickness of the dowel pin, which,as previously indicated, is preferably formed from square or rectangularstock. From these points said arms are extended upwardly parallel toeach other, as indicated at l8, l8, distances approximately equal to theheighth of the dowel pin and thenare directed upwardly and outwardly, asindicated at I9, I9, and finally are directed horizontally outward shortdistances as indicated at 20, 20. In addition, each member I4 and I5 isbent at its portions I8, I8 so that the arms I1, I! below and above thebend are disposed in planes obtusely related to each other.

The member I4 straddles the tubular element or structure I2, I3 and isrigidly secured thereto in any suitable manner, as, for example, bybeing welded to either or both of the pieces I2, I3 adjacent to theirinner ends. The said pieces I2, I3 extend between the arm portions I8,I8 of the member I4 and the latter is disposed relative to said piecesas viewed in side elevation so that when the latter are disposedhorizontally the portions of the arms I1, I! which are disposed belowsaid pieces extend downwardly and toward the outer ends of said piecesand the portions of said arms which are disposed above said piecesextend upwardly and toward the outer ends of said pieces.

The member I5 straddles the dowel pin II and is rigidly secured theretoby welding or in any other suitable manner, the pin extending betweenthe arm portions I8, I8 01 the member I5 and the latter embracing andbeing secured to said pin at a point suitably spaced inwardly from theend portion thereof which is designed to be fixedly embedded in one ofthe slabs Ill. The member I 5 bears the same, or approximately the samerelationship to the dowel pin II as the member I4 bears to the piecesI2, I3. In other words, the

' member I5 is disposed relative to the dowel pin as viewed in sideelevation so that when the dowel pin is disposed horizontally, theportions of the arms II, II below and above the dowel pin extenddownwardly and outwardly and upwardly and outwardly, respectively,toward the adjacent end of the dowel pin. I

In connection with the members I4 and I5 which are rigidly secured tothe pieces I2, I3 and to the dowel pin, respectively, obviously the sameprovide for great facility in locating and supporting the dowel pins andjoint forming structure prior to and during pouring of the slabs,inasmuch as by initially assembling each dowel unit by inserting theproper end of the dowel pin into the related tubular structure I2, I3,the two members I4, I5 cooperate to form in efl'ect a fourlegged stoolfor supporting the dowel and joint forming structure in the properposition.

Although any suitable means may be employed to define an expansion spacebetween the poured slabs, such means is illustrated in the presentinstance as comprising a two-part sheet metal casing designatedgenerally as gl and including slab end defining walls which are capableof movement toward and from each other responsive to expansion andcontraction of the slabs. This casing may be formed in one pieceextending the full length of a joint, or it may be formed in separatesections individual to the respective dowel pin units. If it is formedin one piece, openings are formed therethrough at spaced intervals toaccommodate the dowel pins, and if it is formed in separate sections, adowel pin accommodating opening is formed through each section. As isunderstood, the casing or the casing sections, as the case may be is, orare, as-

sembled with the dowel pins prior to pouring of l the slabs.

In a completed construction the dowel pins are located approximatelymidway between the top and the bottom surfaces of the slabs III, III andas viewed in side elevation, into the slabs in downward and outward andupward and outward divergent relationship, respectively.

Because of the members I4, l5 being fixed to the pieces I2, I3 and tothe dowel pin, respectively, and because of the arms I1, I I of eachmember I4, I5 extending as illustrated and described, any load imposedon either of the slabs obviously is not concentrated in the immediatevicinity of the dowel pins where they pass through the joint formingstructure, but is distributed by the members I I, I5 throughout largeareas of the slabs above and below and to each side of each dowel pin.Thereby rupturing and breaking away of the slabs is eliminated.Moreover, since the arms I1, I! of the members I4, I5 extend from themedial horizontal planes of the-slabs to the bottoms thereof, any loadto which either slab is subjected is transmitted by said arms to thebottoms of the slabs. Thus, the adjacent end portions of the slabsfunction entirely, or substantially entirely, in compression to theexclusion, or substantially the exclusion, of tension, which is anotherimportant reason why the adjacent portions of slabs connected togetherby the present dowel devices are not easily ruptured or broken.Moreover, since the load or stress distributing members I 4 and I5 arelocated with respect to the tubular structure -I2, I3 and the dowel pin,respectively, so that in the completed joint the portions of saidmembers in the immediate vicinity of the tubular structure and the dowelpin are located closely adjacent to the adjacent end faces of therespective slabs, any working of either the tubular structure or thedowel pin in its related slab with the consequent forming of abell-mouthed recess in either slab about either the tubular structure orthe dowel pin, is effectively prevented.

In the Figures 5 to 8 form of the invention the construction is quitesimilar to the Figures 1 to 4 construction and the same advantages areobtained as in the first described construction. Whereas the'load andstress distributing'members I4 and I5 of the Figures 1 to 4 form of theinvention are, however, of one-piece construction, the Figures 5 to 8form of the invention includes a pair of load or stress distributingmembers I4 for the tubular structure and another pair of load or stressdistributing members I 5 for the dowel pin. A very material advantage ofthis is that the separate members I4, I5 may be economically producedeach by a single stamping operation.

Each member I4, I5 comprises a short straight vertical portion I8directed laterally outwardly at its upper end, as at 20 and a portion I1extending downwardly from the portion I 8 at an angle thereto anddirected laterally outward at its lower end as at I6, the said portionsI6, I1 I8 and 20 all being disposed in a common plane.

The portions I8 of a pairo! the members I4 are welded or otherwisesecured rigidly to the outer end of the tubular structure designated asI2, I3 at opposite sides thereof, respectively,

and the portions l8 of a pair of the members i5 are welded or otherwisesecured rigidly to the dowel pin II at opposite sides thereof.respectively, at points spaced inwardly from its end which is embeded inone of the slabs Ill so that in the completed joint the said portions l8are disposed at, or closely adjacent to, the adjacent end surfaces ofthe slabs.' Moreover, thedisposition of the members M, It* relative tothe tubular structure and the dowel pin, respectively, is such that theplane of the portions l6, il and 20 of each member is disposed at anangle of approximately 45 to the dowel pin, with the said portions l6, Hand 20 extending from the portion 3 into the material of the respectiveslabs and the portions l6 disposed horizontally at the bottoms of theslabs. The functioning of the members l4, I5 to distribute stressesimposed on the tubular structure and the dowel pin thus is the same asset forth in connection with the Figures 1 to 4 form of the invention.

As will be observed from Figure 8 of the drawings, the outer end wall ofthe piece l2 of the tubular structure may have its edges bent inwardly,as indicated at H to embrace the outer end portion of the piece l3,thereby to position the outer end of the piece l3 relative to the pieceI2.

Y From the foregoing it will be apparent that the present inventionprimarily includes a dowel B and supports C therefor which not onlyprovide a temporary chair like structure for the dowel as well as thejoint forming means during installation, but which also perform the moreimportant function of a permanent support for the dowel where it emergesfrom the slabs to span the joint space. In their fundamental aspect thesupporting elements are bowed or bent cross-wise of the dowel so thatthe crowns or zeniths of the bends are relatively back to back at thepoint where the critical stresses are focused on the dowel. In otherwords, the supporting elements C are of wing-back or wedge formation asviewed in side elevation and the arms of the wings or wedge arerelatively radially disposed to the dowel at an oblique angle. Thus thefocused stresses are deplayed and distributed in the material of theslab so that chafing or abrasion between the dowel and concrete isavoided and the material of slab ends is strengthened because it is incompression throughout its beam loading depth.

Without further description it is thought that the features andadvantages of the invention will be readily apparent to those skilled inthe art, and it will of course be understood that changes in the form,proportion and minor details of construction may be resorted to, withoutdeparting from the spirit of the invention and scope of the appendedclaims.

I claim:

1. Connecting means for a pair of slabs comprising a dowel pin extendingbetween and into the slabs, a tubular structure embedded in one of theslabs and slidably accommodating the related end portion of the dowelpin. and means for dispouring of the tributing stresses to which thetubular structure is subjected when either slab is loaded, said meanscomprising arms rigid with said tubular structure directly adjacent tothe end face of the related slab and extending upwardly and outwardlyand downwardly and outwardly, respectively, from said tubular structureinto the material of the slab.

2. Connecting means for a pair of slabs comprising a tubular structurecomprising a pair of interfltting U-shaped pieces embedded in one of theslabs, a dowel pin embedded at one end in the other slab and having itsother end slidably engaged in said tubular structure, arms rigid withthe tubular structure extending downwardly and outwardly therefrom intothe material of the related slab, and arms rigid with the dowel pinextending downwardly and outwardly therefrom into the material of theother sla 3. A reinforced joint for concrete road slabs comprising incombination with an expansion joint structure extending verticallythroughout the depth of the adjacent slabs and adapted to rest on thesub-grade, a reinforcing dowel extending between said adjacent slabs andthrough the said expansion joint structure, and reinforcing membershaving a supporting connection with the dowel on each side of the jointand including reinforcing elements extending from the sides of the jointinto the slabs above and below the dowel and away from the joint andalso-including base portions adapted also to rest on the sub-grade tosupport the entire unit during the concrete or equivalent plastic.

4. A reinforced self-supporting joint unit for concrete road slabs,comprising, in combination, with an expansion throughout the depth ofthe adjacent slabs and adapted to rest on the sub-grade, a reinforcingdowel extending between said adjacent slabs and through the'saidexpansion joint structure, and reinforcing members engaged with saiddowel to prevent rotation thero said members being arranged on each sideof the joint and including reinforcing elements diverging from the sidesof the joint 'at the location of the dowel into the slabs above andbelow the dowel and also including base portions adapted to rest on thesubgrade to support the entire unit during the pouring of the concreteor equivalent plastic.

5. A reinforced self-supporting expansion joint structure for concreteroadways, comprising, in combination, an expansion joint having loadtransferring dowels extending through the same and to opposite sidesthereof for embodiment in adjacent concrete slabs, reinforcing membershaving a supporting engagement'with the dowels adjacent the sides of thejoint, each reinforcing member including reinforcing elements extendinginto the slabs above and below the dowel, the portions of said elementsextending below the dowel including base portions adapted to support andbrace the entire unit during the pouring of the concrete.

- WALTER F. SCHULZ.

joint extending vertically'

